The present invention relates to a process and a system for removing sulfur oxide and carbon monoxide from a gas stream. More particularly, the present invention relates to a process and system for the removal of sulfur oxide and carbon monoxide from a flue gas stream with an oxidation step using a reduced amount of combustion air which also results in a reduction of the amount of nitrogen oxide.
Combustor flue gas streams are typically desulfurized by injection of reactive solids such as lime or limestone, or by scrubbing in an alkaline aqueous solution. These treatments have varying degrees of effectiveness in removing SOx and do little to reduce NOx. The amount of air fed to combustors is usually maintained at greater than 110% of the stoichiometric requirement for complete combustion of fuels containing hydrogen and carbon to water and carbon dioxide. One reason for this amount of excess air is to ensure complete combustion of carbon monoxide to carbon dioxide.